This invention relates to an endoscope system provided with a luminance adjusting apparatus.
In some endoscope systems, an associated or auxiliary apparatus such as a dual viewing optical unit or camera unit is attached to an eyepiece section so that two or more operators may simultaneously observe the interior of a body cavity, or that the region of interest in the body cavity may be photographed.
In an endoscope system in which a light transmitted from a light source unit through a light guide is projected on the region of interest and a light reflected from the region of interest is transmitted to an eyepiece section through an image guide so that an image of the region may be viewed, when a dual viewing optical unit, a camera with a photometric beam splitter, or a TV camera with a beam splitter capable of simultaneous observation and photographing is attached to the eyepiece section, the light beams supplied to main and auxiliary observation light paths is reduced by the beam splitter, failing to provide a sufficient observation light. When the associated or auxiliary apparatus is removed from the eyepiece section, on the other hand, the beam supplied to the main observation light path will be too large to keep a proper degree of brightness.
Conventionally, therefore, luminance is adjusted by a mechanical stop disposed between a light source lamp and the incidence end face of the light guide, or an electric power control circuit for controlling electric power supplied to the light source lamp.
With the prior art systems, however, the operator must manually regulate luminance with every attachment or detachment of the auxiliary apparatus. Thus, the operation is complicated and troublesome, and the observation time will be prolonged to cause increased pain to a patient.